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Biomedical subjects

R Rylander

Publications and source records attributed to R Rylander.

At least 91 records · Page 5Linked to original sources

Diseases associated with exposure to plant dusts: focus on cotton dust.

Research during recent years has made clear that pulmonary disease and certain general symptoms caused by organic dusts are far more common than previously suspected. To the traditional environments of cotton dust and moldy hay has been added a series of environments, such as swine confinement buildings, sewage treatment stations and industrial fermentation plants. It has been suggested that, rather than linking clinical disease with a specific environment (farmer's lung, byssinosis, etc), symptoms should be related to the relevant pulmonary cellular reactions, particularly inflammation. In so doing, a more homogenous picture of the various clinical entities has emerged. It is now understood that symptoms once considered to be unique to one particular environment, such as chest tightness in cotton mills, are also present in other organic dust environments. New models for organic dust-induced disease have been established using the criteria developed for disease among workers in cotton mills and swine confinements buildings. This has led to uniform methods for diagnosis, description of symptomatology and understanding of pathogenesis. Employing this experience on an international basis, provides an important background for dealing with new problems in this important area of occupational health and is a prerequisite for the establishment of treatment and prevention programs.

Byssinosis↗

Reduction of alveolar-capillary diffusion after inhalation of endotoxin in normal subjects.

Normal subjects were exposed to an aerosol of Escherichia coli endotoxin. Carbon monoxide diffusion (Dco), spirometry, blood neutrophils, white blood cells, and platelets were determined at various times thereafter. A significant decrease in Dco and an increase in blood neutrophils was found, with a maximum effect 4 to 8 h after exposure. Exposure to distilled water caused a tendency for Dco to decrease and a significant increase in blood neutrophils. No effect on spirometry or body temperature was detected. It is suggested that the changes observed represent an inflammation at the alveolar level that appears at dose levels of endotoxin below those which cause bronchoconstriction and fever.

Administration, Inhalation↗

[The epidemiologist facing assessment of low risk].

Epidemiological studies on low risks involve a number of major methodological difficulties. This review defines the concept of low risk and emphasises the need to control all large, possibly disease-related risk factors, before low risk factors can be evaluated. This procedure is also essential in identifying confounding factors. There is a special need to evaluate statistical power in studies on low risk factors, and the representativeness of both cases and controls should be carefully verified, particularly in case-control studies. The need to control the researcher's wish bias and the main requirements for meta-analysis are also presented.

Case-Control Studies↗

Lipopolysaccharide (LPS) inhalation in healthy subjects increases neutrophils, lymphocytes and fibronectin levels in bronchoalveolar lavage fluid.

Bacterial endotoxin has been suggested as responsible for the development of subjective symptoms and transient or chronic lung function impairment seen after exposure to organic dusts in cotton mills, poultry houses, swine confinement buildings and saw mills. Animal experiments have demonstrated bronchoalveolar neutrophilia being the most prominent cell response in animals following bacterial lipopolysaccharide (LPS) inhalation. The present study was conducted to obtain information on some aspects of the early inflammatory response to inhaled LPS in man. Eight healthy nonsmoking subjects, 23-27 yrs old, underwent bronchoalveolar lavage (BAL), 3 h after a provocation test with 100 micrograms LPS from E. coli dissolved in 2 ml isotonic NaCl. The solution was aerosolized with a jet nebulizer and inhaled. The calculated dose delivered to the lung was approximately 25 micrograms, which equals exposure in some occupational settings. The BAL data for each individual subject were compared with data from a control BAL performed at least 6 weeks prior to the LPS challenge. The major cellular response to LPS, reflected in BAL fluid, was an approximately hundredfold increase in neutrophils. The total number of lymphocytes was on average tripled. The alveolar macrophage phagocytosis of opsonized yeast particles in vitro was significantly reduced. A further indicator of an ongoing inflammation was an increase in fibronectin. No changes were seen in the levels of BAL albumin, indicating that the elevated level of fibronectin could not be explained by an increased permeability, but rather by a local production. The results correspond with data from animal studies and further supports the hypothesis that bacterial LPS is important in the pulmonary reaction induced by organic dusts.

Administration, Inhalation↗

Tumor necrosis factor and interleukin-1 activities in free lung cells after single and repeated inhalation of bacterial endotoxin.

Bacterial endotoxins (lipopolysaccharides), important components of many organic dusts, are known to induce macrophages to produce the inflammatory mediators interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-alpha). To investigate the role of these mediators in the early inflammatory responses in the lung, guinea pigs were exposed to an aerosol of bacterial endotoxin. A bronchoalveolar lavage (BAL) was then performed, and TNF-alpha and IL-1 in lysed BAL cells and in the supernatants from BAL cell cultures were studied. The effect of single and repeated LPS inhalation exposures on the activities of TNF and IL-1 was studied, as was the effect of LPS added to the cell culture medium. A single inhalation exposure to LPS caused an increase in the TNF-alpha and IL-1 activities in cell lysate and in the cell culture supernatant. After a second inhalation exposure, cell-associated and extracellular TNF-alpha activity could not be detected, whereas IL-1 activity was markedly enhanced. IL-1 activity was increased when LPS was added to the cell culture medium with or without a prior inhalation exposure. In contrast, TNF-alpha activity was not affected after a second exposure.

Administration, Inhalation↗

Magnesium and calcium in drinking water and cardiovascular mortality.

Data on the hardness of drinking water were collected from 27 municipalities in Sweden where the drinking water quality had remained unchanged for more than 20 years. Analyses were made of the levels of lead, cadmium, calcium, and magnesium. These water-quality data were compared with the age-adjusted mortality rate from ischemic heart and cerebrovascular disease for the period 1969-1978. Lead and cadmium were not present in detectable amounts except in one water sample. A statistically significant inverse relationship was present between hardness and mortality from cardiovascular disease for both sexes. Mortality caused by ischemic heart disease was inversely related to the magnesium content, particularly for the men (P less than 0.01). The rather small set of data supports results from previous studies suggesting that a high magnesium level in drinking water reduces the risk for death from ischemic heart disease, especially among men, although the possible importance of confounding factors needs further evaluation.

Cadmium↗

Experimental allergic alveolitis after exposure to different microorganisms.

The experiments described here examined the capacity of different microorganisms to induce allergic alveolitis. Guinea-pigs were exposed to an aerosol of pure cultures of five different organisms, four of which are common in mouldy hay, without previous injection of an adjuvant. The animals were either acutely exposed or exposed for 3 to 5 weeks, after which the numbers of different inflammatory cells in the airways were counted and histological changes in the lung parenchyma were assessed. It was seen that prolonged exposures to large numbers of spores produced a cellular infiltration in the alveolar and bronchiolar region, and gave rise to lesions resembling early granulomas. The number of lymphocytes increased in the airways. The results suggest that allergic alveolitis can be induced by inhalation of various kinds of microorganisms and that these may vary in their capacity to produce the disease.

Allergens↗

Health effects of cotton dust exposures.

The characteristics of the effects of exposure to cotton dust were adequately described more than 50 years ago. Symptoms of airway irritation, cough with or without phlegm, and Monday morning chest tightness are typical. The symptoms caused by exposure to cotton dust are similar to those induced by other organic dusts. A common pathology is acute or chronic inflammation, and bacterial endotoxins seem to be the causative agents for the acute and some chronic reactions.

Asthma↗

Bronchial hyperreactivity among pig and dairy farmers.

The presence of work-related symptoms, pulmonary functions, and bronchial reactivity were studied in farmers working with dairy animals or pigs. An increased incidence of the organic dust toxic syndrome, cough, and throat irritation was found. Pulmonary function baseline values were close to normal, and no significant decreases occurred over the work period. Bronchial reactivity was increased.

Animal Husbandry↗

Lung cancer risk and mutagenicity of tea.

To study the possible association between drinking tea and lung cancer, epidemiological and experimental materials were collected from the Chinese population in Hong Kong. In a retrospective study of 200 female lung cancer patients and 200 matched controls, all subjects were interviewed concerning their eating habits, smoking histories, and lifetime exposures to environmental pollutants. Analysis of the data demonstrated an adjusted and statistically significant increased lung cancer risk of 2.7 among those who drank green tea. Several brands of tea commonly drank in Hong Kong were assayed for mutagenicity using Ames' assay. Significantly elevated levels of mutagenic activity were found to be present after metabolic activation using cell-free extracts of cecal bacteria from rats. These data suggest that further research is needed to understand the possible consequences to human health of ingestants taken at low doses but long duration over the normal lifespan, and the possible interactive effect between mutagens in tea and other ingestants and inhalants in human cancer etiology.

Case-Control Studies↗

Environmental exposures with decreased risks for lung cancer?

The case for a decreased risk of lung cancer after exposure to environmental agents is evaluated using toxicological and epidemiological data. Experimental evidence demonstrates that exposure to substances which produce an inflammatory response in the lung, such as bacterial endotoxins, causes an increase in the secretion of inflammatory mediators and substances with a particular effect on tumour cells such as tumour necrosis factor (TNF). Other irritant agents, such as tobacco smoke, may also induce an activation of macrophages at low levels of exposure. Epidemiological evidence from several studies suggests that people exposed to dusts containing bacterial endotoxins have a lower lung cancer incidence than those who are unexposed. There are also some data suggesting that in certain ethnic groups, females smoking a small number of cigarettes/day, might have a lower risk for lung cancer than non-smokers. These data provide support for a hypothesis that low-dose exposures to some air pollutants might result in a decreased risk of lung cancer.

Cause of Death↗

A clinical and endocrine study on the effect of orally administered bacterial endotoxin in adult pigs and goats.

Endotoxin of Gram-negative bacteria was orally administered in 5 female pigs and 8 male goats. Two of the gilts were pregnant. A solution of lipopolysaccharide (LPS) of Enterobacter agglomerans was mixed into the feed ration of the pigs (40 mg/animal), and given by gastric tube into the rumen of the goats (1-20 mg/animal). Jugular venous blood was collected and clinical signs, rectal temperature and WBC counts were recorded for 12-24 hours. Plasma concentrations of the major plasma metabolite of PGF2 alpha, 15-keto-13,14-dihydro-PGF2 alpha were determined in both species, progesterone concentration only in pigs. The pigs showed slight to severe signs of endotoxemia. Increases in rectal temperature and levels of the PGF2 alpha metabolite occurred in 3 gilts. Progesterone level and the total WBC counts remained unchanged. Differential counts followed irregular patterns mostly within the normal range. The goats showed slight signs of discomfort. Temperature increased in one animal. No other parameters were altered after the intake of LPS. The observations in pigs indicate that endotoxin either penetrated the intestinal barrier causing systemic endotoxemia or induced inflammatory reactions in the intestine activating inflammatory mediators.

Administration, Oral↗

Increased blood monocyte procoagulant activity in cotton mill workers.

Blood monocyte procoagulant activity has previously been related to delayed type hypersensitivity. In this study, cotton workers exposed to cotton dust containing endotoxin and subjects not exposed to organic dusts, were examined. Blood mononuclear cells from the two groups were incubated with and without endotoxin and the recalcification time was measured. Mononuclear cells from cotton workers had a decreased baseline procoagulant activity but an increased response to endotoxin, suggesting cellular sensitization to the endotoxin present in cotton dust.

Blood Coagulation Factors↗